MAXON—STUDIES OF TROPICAL AMERICAN 
Segments acute to long-acuminate or caudate. 
Fronds relatively small, the pinne 4.5 cm. broad, or 
less; segments arcuate, abruptly acuminate- 
cuspidate; veins 12 to 14 pairs, mostly once- 
forked; sori supramedial to submarginal. . ... 
Fronds very much larger, the pinne 7 to 22 cm. 
broad; segments (or pinnules) long-acuminate 
to caudate; veins 16 to 18 pairs, twice to sev- 
eral times branched; sori medial or in a broad 
medial zone. 
Segments 20 to 23 pairs, linear-oblong, long- 
acuminate, only the subcaudate apices 
conspicuously crenate-serrate; veins 
about 16 pairs, alternately 2 to 4- 
branched.............-.-------+--+-0+- 
Segments about 28 pairs, deltoid-lanceolate, 
deeply crenate or crenately lobed, the 
apices usually linear-caudate, sharply 
serrate-crenate; veins about 20 pairs, 
with 4 to 8 pairs of mostly simple, pin- 
nately arranged branches. .....--.----- 
Veins (basal) regularly united by a transverse veinlet, forming a 
single series of costal areoles. 
Lamina bipinnate........-------2-- 2 eee eee eee ere 
Lamina pinnate to very deeply bipinnatifid (or, as to larg- 
est pinnz, bipinnate in no. 11). 
Pinne subentire to serrate, crenate, or lobed not more 
than half way to the costa. 
Margins lightly and remotely crenate-serrate; 
pinne decurrent....-..--------+---------- 
Margins deeply crenate, crenate-serrate, or cre- 
nately lobed; pinne not decurrent. 
Veins (excepting those joined to form basal 
arches) simple; pinnse deeply crenate. 
_ 
Major crenations 5 to 7 mm. broad at sin- 
uses, short-apiculate distally; pinn 
2.5 to 3 cm. broad... .-..--------- 
Major crenations 6 to 12 mm. broad at 
sinuses, never apiculate; pinne 
3 to 4.2 cm. broad. 
Basal vein of each side joined to 
opposed basal vein of next cre- 
nation by a transverse veinlet, 
then produced and commonly 
joining the second vein of its 
own group; crenations 9 to 12 
mm. broad at sinuses. .....---- 
Basal vein of each side similarly joined 
to opposed basal vein of adja- 
cent crenation, the veins other- 
wise all free; crenations mostly 
6 to 8 mm. broad at sinuses. . - . 
Veins mostly once-forked; pinne distinctly 
lobed one-third to one-half the distance 
to the costa............2.------+--+++- 
FERNS. 
9 
11 
13 
14. 
15 
. IT. apiculata. 
. H. subglabra. 
. A. grandis. 
. H. petiolata. 
. HH. decurrens. 
IT, mexicana. 
. A. lucida. 
29 
16. H. guatemalensis. 
. A. choricarpa. 
